Current toilet fill valves provide water both to fill the toilet tank and to fill the toilet bowl. Preferably, the filling of both is completed at the same time. In typical fill valves, a large flow is sent to refill the toilet tanks and a small flow is sent to refill the toilet bowl. In some designs, the large flow into the tank comes from an orifice at the bottom of the valve, whereas the small flow into the bowl comes from a small tube at the top of the valve, wherein the small tube is directed into the flush valve's overflow tube.
Since the volume of the toilet tank is larger than the volume of the toilet bowl, traditional valves employ flow control valves that restrict some of the flow going into the toilet bowl (such that the refilling of both tank and bowl is completed at the same time).
Unfortunately, by restricting the flow to the bowl, the internal valve pressure in the fill valve is increased. This in turn increases the sound level of the refilling. An ideal solution to this problem would not increase system refilling noise.
Another problem common to existing products are that they are simply not accurate enough. Rather, the toilet bowl fills too quickly or too slowly (as compared to the refilling of the tank). Ideally, it would instead be desirable to have an adjustable mechanism such that the various percentages of water diverted to either the tank or the bowl could be finely adjusted.
Yet another problem with existing flow control valves is the problem of siphoning. Siphoning occurs when the toilet becomes flooded (or the water pressure from the building drops) such that water is pulled back from the fill valve into the building's plumbing. A danger with existing fill diverters is that should such a siphon flow start to occur, it is important that the fluid path between the toilet bowl and the building plumbing be broken immediately such that water from the toilet bowl cannot be drawn back into the building's water supply.